Electric clock mechanism



Feb. 7, 1939.

I ELECTRIC CLOCK MEGHANISM Filed March 2, 1936 2 Sheets-Shet 1 I Mg III

J. w. HOBBS 2,146,119

Feb. 7, 1939. J. w. HOBBS 2,146,119

ELECTRIC CLOCK MECHANISM Filed March 2, 1936 2 Sheets-Sheet 2 Q),INSULATION ME I U L 0//77/7 /70%%S Patented m. 1, 1939 PATENT- OFFICE2,140,119 amc'rnrc cnocx MECHANISM John w. Hobbs, Chicago; m., assignorid The George W. Borg Corporation, Chicago, 111., a corporation ofDelaware Application March 2, 193d, Serial No. 66,532

4Claims.

to provide an improved automatic winding mechanism for a spring drivenclock.

Another object is the provision of an electrically actuated windingmechanism for a clock, which is automatically deenergized when the clockis wound and energized'when the clock approaches a run down condition.

A further object of the invention is the provision, in a clock of thecharacter described, of protective means for preventing overheating and'possible damage of the winding mechanism, due to abnormal energizationthereof.

It is also an object of this invention to provide a protective devicewhich will automatically disconnect the winding mechanism relative tothe electrical source when abnormal heating occurs, and which will alsooperate to automatically reconnect the electrical supply as soon as thewinding mechanism has cooled to a safe operating temperature.

A still further object resides in the provision of novel means wherebyactuation of the timing mechanism will becontinued without interruptionduring the interval in which the winding mechanism is being rewound.

In accordance with the general features of the preferred form of theinvention, it is proposed to.

provide a conventional timing mechanism having a main driving gear whichis retained against reverse movement. by means of a detent pawl. maindriving gear is actuated in a forward direction by means of springpressed pawls carand that for rewinding the clock, energization of i themagnet will move the armature to a new position, thereby againtensioning the actuating driving spring.

The rewinding is accomplished automatically by means of a switch whichis actuatedin response to the movement of the armature, so that as thearmature reaches a run-down position, the

switch is closed to energize the electro-magnet The,

and return the armature to a position wherein the driving spring isagain stressed. At this position, the movement of the armature operatesto open the switch and demagnetize the electromagnet.

The automatic winding device is arranged to operate from the storagebattery of the automobile, and it has been found that when the batteryis low. or during starting of the car, particularly in the winter time,there is insumcient voltage to 10 energize the electro-magnetsufficiently to move the armature and open the deenergizing switch incircuit with the electro-magnet winding. Under these conditions, theelectro-magnet is energized for anabnormal period of time, with the 15result that the coil of the electro-magnet becomes overheated and thereisv a possibility of its being burned out or otherwise damaged.

To overcomethis condition and protect the coil, it is proposed as anadditional feature of the 20 invention to provide a thermostatic switch,which will open the electro-magnet winding circuit when abnormalenergization of the electro-magnet occurs. This switch consists of abimetallic strip which, due to the flow of current for an 25 abnormalperiod, will be flexed away from an associated contact and open thecircuit. After a brief interval of approximately one minute, thebimetallic strip will have cooledsufiiciently to re-establish theconnection to the electro-mag- 30 net, whereby the armature will againbe attracted to restress the spring. As soon as normal operatingconditions are established with normal battery voltage, the thermostaticswitch will remain closed and the switch which is 8.61111:- 35 ated inresponse to the movement of the armature will again function toautomatically ener gize and deenergize the electro-magnet and keepthemainoperating spring stressed at all times.

' In order to prevent the clock from stopping during the rewinding orrestressing of the main driving spring, a novel secondary orsupplemental drive is provided. For this purpose, a spring connection isprovided between the main driving gear and the driving shaft, the maingear being 5 mounted for relative movement on the shaft. This. spring isstressed during the time when the clock is being driven by the maindriving spring and will continue the drive of the clock for a briefinterval, during which time the elec- 5o tromagnet may act on thearmature to again rewind or stress the main driving, spring. The

operation of the foregoing features will be more apparent from thefollowing description.

Other objects and features of the invention will 55 mostatic switch forthe electro-inagnet of the winding mechanism, taken substantially on.the line IV--IV of Figure 1;

Figure 5 is an elevational view showing the details of theelectro-magnet and the thermostatic protective switch, when viewed fromline V--V of tially on the line VI-VI of Figure 1.

Figure 4; and

Figure 6 is a detail view in section showing the operative relationshipbetweenrthe' parts of the secondary. driving mechanism, taken As shownon the drawings: Figure 1 of the drawings illustrates a clock whichembodies the features of the present invention.- This clock is composedof a. timing so mechanism, generally indicated at A, having aconventional escapement, gear train, hands and dial; and power means,generally indicated at B, including a main driving spring and anelectrical rewind for intermittently stressing the main drivins spring.

The timing mechanism includes a main shaft I 0 for driving the minutehand, this shaft having secured thereto for rotation therewith a pinionI I which, through the usual train of gears, drives the hour hand of theclock. A hub I2 '-is rotatably mounted on the shaft I0 and carries atone end a gear I3 which drives the escapement mechanism. This'end of thehub is connected to a spring Id, which spring is rotatable with thepinion II andfrictionally engages the side face of the gear, I3, thusenabling movement of the hands for setting the clock independently ofthe driving mechanism.

The opposite end of the hub I2 is formed with a peripheral flange I2awhich cooperates with a centrally disposed extension .I2b of the hub todefine an annular groove I3a. A main driving gear I5 is rotatablysupported on the extension I2b and is held in abutment with the outeredge of the flange I2a by a washer I3b over which the end of theextension is turned back as shown at Ila, sufiicient clearance beingmaintained to permit rotation of the gearJ5 on the extension.

It will be apparent that'thehub l2, gear I3, and gear I5 provide aunitary assembly on the shaft III, which is 'frictionally connected withthe pin.-

. ion through the spring II. The hub I2 latetained against movementaxially of the shaft I ll,

away from spring Il, by means of a collar Ilb on the shaft, this collarforming an abutment for an internal shoulder I5a of the hub bore.

'- Movement of the gear I5 relative to the hub is limited by aprojecting stud I5b on the gear I5, which is movable between the ends ofan opening I50 in the peripheral flange I2a of the hub.

The gear I5 is connected to the hub through a spring I6 disposed in thegroove I3a, one end 'of this spring being anchored in the gear I5 andthe other end in the hub. with the foregoing arrangement, a secondarydrive for the clock is substanprovided, which prevents a cessation orstopping of the timing mechanism during the interval when the maindriving spring is,being stressed or rewound.

As shown in Figure 6, it will be evident that movement of the gear I5 ina forward direction to the limit of its movement will stress the springIS in such a manneras to drive the hub I2 for a short interval of time.

There is also rotatably supported on the shaft III for independentmovement at one end of the hub an armature I I. This armature comprisesoppositely extending arm portions I8 and I9 which are deflected at theirends to form right angularly disposed projections 20 and 2I which definepole pieces cooperatively associated with the respective poles 22 and 23of an electromagnet.

Each arm of the armature carries a. pivotally mounted pawl 24 havingteeth at its free end .for engagement with the teeth of the main drivi 8gear I5. The pawl. 24 is resiliently moved into engagement with the gearI5 by means of a spring 25 having one end in engagement with the-pawland its other end engaging a stop pin 26. The pawls E l-24 permit freemoveme of the armature in a counter-clockwise direction .relative to thegear I5, but on movement of the armature in a clockwise direction, thearmature and gear I5 will move as a .unit.. Movement of the gear I5 in acounter-clockwise direction, when the armature is being moved in acounterclockwise direction, is prevented by means of a detent pawl 21.The pawl 21, however, will permit free clockwise movement of the gearI5.

Movement of the armature in a clockwise direction to actuate the timingmechanism is accomplished by means of a spring 28 having one endanchored, as at 29, to the armature,and its\ other end anchored, as at30, to a bracket member 3| which is fixedly supported on the clockframework.

With the foregoing arrangement, it will be seen that when the armatureis rotated in a counter-clockwise direction, the spring 28 will 45 betensioned and the energy stored in this sprin may be'utilized to drivethe clock mechanism for a limited interval of time. armature in acounter-clockwise direction is accomplished by energizing theelectrc-magnet of the winding mechanism.

The electro-magnet is supported on a back plate 320i the frame structureby means of small projections 33 on thepole pieces 22 and 23, re-

, spectively, these projections extending through suitable openings inthe back plate-and bein peened over. i

Movement of the,

Referring to Figure 1, it will be noted that the core of the.electro-mas'net comprises a plurality of iron laminations 3.4 havingtheir .ends' extend-. ing into openings 35 in the faces of the poles 22and 23 of the electro-magnet. core of the magnet isa coil winding 36which in this instance is designed to operate on from 3.2 to 20 volts.

Surrounding the By energizing this coil: from a suitable source,

anism without any attention from the operator of the automobile.

It will be apparent that when the armature is moved in acounter-clockwise direction, the force of the main driving spring 28becomes ineflective to drive the timing mechanism. It is durin thisinterval that the secondary drive, by means of the spring I6 comesinto.play and drives the timing mechanism as previously described for ashort interval, this interval being sufficiently long to permittensioning of the spring 28 by movement of the armature, after which themain driving spring again drives the timing mechanism. The spring IEwill be reenergized by movement of the armature in driving the timingmechanism.

Intermittent energization and deenergization of the coil winding of theelectro-magnet is accomplished by a switch which is actuated in responseto the movement of the armature. This switch comprises a pivotallymounted arm 31 which is supported for rotational movement on anintermediate pivot 38. This pivot is supported on a bracket 39 which issecured to the back plate 32. One end of the switch arm 31 is providedwith a contact 40 which is arranged to engage with a contact 4| to openand close the circuit to the coil winding of the electro-magnet.

The contact 4| is secured to the outer end of a metallic strip 42,having its other end insulatingly anchored at 43 to the supportingbracket 39 Snap action of the switch is accomplished by moving it past adead center position. The opposite end of the arm 31 from the contact 40is provided with a V-shaped notch 44 for receiving the notched end of alink 45, the other end of this link being also notched, as shown at 46,to receive therein the free end of a spring member 41 which is anchoredat its other end, as shown at 48, to the bracket 39. The bracket 39 alsocarries a stop member 49 for limiting movement of the arm 31 of theswitch away from the stationary contact assembly.

It will be observed that as the switch arm 31 and link 45 are broughtinto alignment by movement of the switch arm, the spring 51 will bestressed. Further movement of the switch arm will cause the spring 41and link 45 to pass the dead center position, and the spring 41 willforce the contacts as and 4! to be engaged or disen-' gaged with a snapaction.

Opening and closing of the switch is accomplished in response tomovement oi. the armature by providing an angularly projecting armportion at which is integrally formed with the switch arm Eli, thisprojecting arm portion at its outer endgbeing formed to define angularlydisposed arms 3i and 52 which are so disposed as tobe engageable by apin 53 on the armature.

It will be observed that when the contacts 40 and M are in separatedposition, when the switch is open, the arm is so disposed as to beengage'able by the pin 53 when the armature is moved in a clockwisedirection and nears the limit of its movement, at which time it isdesirable to rewind the driving mechanism. Movement of the switch toclosed position will act to bring the arm 52 into the path. of travel ofthe pin 53, so that when the armature is moved in a counter clockwisedirection by virtue of the electro-magnet being energized, the switchwill again be opened to deenergize the electro-ma'gnet coil winding asthe armature comes to its limit of movement in a counter-clockwisedirection. It will therefore be evident that with this arrangement thedriving mechanism is automatically and intermittently wound.

In the operation of the clock mechanism thus far described, it has beenfound that with a low battery or when cranking a car in the winter time,there is insuillcient voltage to sufiiciently energize theelectro-magnet to move the armature in a counter-clockwise direction tothe full limit of its movement in a counter-clockwise direction. Inother words, instead of a full movement of the armature, the movement isonly a partial movement, and while this movement will stress the maindriving spring 28 a suflicient amount to continue the operation of thetiming mechanism, the partial movement is not sufficient to cause anopening of the contacts 40 and 4| to deenergize the electro-magnet coil.Under these conditions, the electro-magnet will in a short time becomeoverheated and may burn out or otherwise be damaged. Inorder to overcomethis condition, an additional protective switch is provided in theenergizing circuit of the electromagnet coil.

This switch comprises a U-shaped strip of bimetallic metal 54 having oneleg anchored, as shown at 55, to form an electrical connection orterminal and secure the bimetallic strip to a base 55 of suitableinsulation material. The free end of the strip of bimetallic material isassociated with the free end of a contact member 51 which is anchored atits other end to the insulation base and forms a terminal 58. It willthus be evident that the bimetallic strip and contact element 51 are in"the circuit and carry current. The flow of abnormal current through thebimetallic strip will cause the free end portion of the strip to beflexed away from the contact element 51 and thus open the circuit.Snap-action of the contact members in opening and closing the circuit isaccomplished by providing a spring member 59 having one end anchored tothe insulation base and its other end deflected as shown at 60 to form aV which overlies the end of the bimetallic strip when the bimetallicstrip is in contact with the contact element 51 and serves to delay theopening of the contacts until the forces deflecting the bimetallic stripare sufficient to overcome the action of the springs 59, whereupon thebimetallic strips snaps past the deflected end of the spring 59. Returnof the bimetallic strip to a position in contact with the contactelement 51 islikewise delayed by the deflected end of the spring 59until sufficient force has-been built up to overcome the action of thespring 59, whereupon the bimetallic strip snaps past the deflected endof the spring 53 and engages the contact element 51 positively. Inoperation, the thermostatic switch will heat up and open its contact inabout twenty seconds, and will close its contact, upon cooling of thebimetallic strip, in about one minute. In other words, the thermostaticswitch provides a relatively quick opening and delayed closing of itscontacts.

The thermostatic switch intermittently energizes and deenergizes theelectro-magnet coil under abnormal conditions in such a manner that thecoil is not overheated and there is no possibility of damage. As soon asnormal conditions of excitation are established, the thermostatic switchwill remain closed, and the automatic operation will then be by means ofthe switch which is opened and closed in response to the movement of'thearmature.

The electrical connections to the clock are 75 shown schematically inFigure 1. A storage bat-' tery or other source oipower is indicated'atll.

-As in the usual installation in automobiles, one

side of the battery is grounded at 82 and the other 'side is connectedthrough a conductor 63 to a terminal $4 on the back plate, this terminalbeing insulated from the' back plate of the clock. A second irminal 65is also provided and is grounded, as at 68, to complete the connectionto the battery.

The energizing circuit of the electro-magnet coil is from the terminalthrough a conductor 86 to the terminal 58 oi. the contact element 51,

through the thermostatic strip 54 to the terminal. 55, the conductor 86to one end of the coil 36,-

parent that the present invention provides an improved electricallyactuated winding mechanism, whereby a clock of the spring driven typemaybe automatically wound; wherein the winding of the clock is entirelyautomatic; an electric clock in which the electrical mechanism is pro- Ihave described in detail the preferred embodi-,

tected against overheating and possible damage; and in which novelsecondary power means are provided for driving the timing mechanism fora short interval during which the main driving. mechanism is beingenergized.

It is of course to be understood that although ment of my invention, theinvention is not to be thus limited, but only insofar as defined by thescope and spirit of the appended claims.

I claim as my invention:

1. A clock comprising a rotatable drive shaft, a first member fordriving the shaft, a second member rotatably mounted on the firstmember, saidmembers being connected for limited relative rotationalmovement, whereby the second member may drive the first member when thesecond member is rotated in one direction, a secondary spring connectingthe members for rotating the first member when the second member ismaintained stationary, means preventing rotation of the second member inthe opposite direction, a main spring arranged for rotating the secondmember in the first direction, and mat. for intermittently energizingthe main spring.

2. A clock comprising a rotatable drive shaft,

a first gear having a hub in driving connection with said shait, a maindriving gear rotatably mounted for limited relativerotational movementon said hub, whereby the main driving gear may drive the first gear whenthe main driving gear is rotated in one direction, a secondary springconnecting said gears for rotating the first gear when the main drivinggear is maintained stationary, means preventing rotation of the maindriving gear in the opposite direction, a main spring for rotating themain driving gear in the first direction, and means for intermittentlyenergizing the main spring.

3. A clock comprising a rotatable shaft, a first gear rotatable on saidshaft, a friction connection between said gear and shaft, a second gearhavlng a limited relative movement connection with the. first gear,whereby said second gear may drive the first gear after limited movementin one direction, a secondary spring connecting said gears for rotatingthe'first gear when the second gear is maintained stationary, meanspreventing rotation of the second gear in the opposite direction, meansincluding a main driving spring for rotating the second gear in thefirst direction, means for intermittently energizing the main spring, anescapemen't mechanism driven from the first gear, and a time indicatingmember driven from said shaft.

4. An electric clock comprising a frame structure, a driving mechanismincluding a winding magnet having a coil adapted to be energized from anelectric circuit, and a thermostatic switch for opening and closing thecircuit to said coil with a snap action in response to an overloadcurrent for a relatively short .interval of time or a normal current fora relatively longperiod of time, said switch comprising a U-shapedthermostatic strip disposed in close proximity to said coil and anchoredat one end, the other end being free for deflection, a fixed contactmember having one end disposed for normal engagement by said free end,and a spring member delaying movement of the free end out or and intoengagement with said contact, said contact and thermostatic strip beingconnected in said electrlc circuit. JOHN W. HOBBS.

